migration from 2 to 3

I've seen message that v.3 has been wrote from the scratch and it is not possible to upgrade from 2 to 3. However functions included in version 3 are so tempting that I started to think about migration. Certainly I am going to wait for stable version 3 and I am sure that not only I am thinking about migration from 2 to 3. It may take some effort or manual job, but that would be great hearing somebody have done it succesfuly and can share some tricks.